1. Field
This application relates generally to an elevator interior illumination assembly comprising LED lamps and capable of operating on either a primary elevator electrical power source or, in the event of a loss of same, a backup power source.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
By law, elevators must be fitted with illumination assemblies capable of providing emergency backup interior illumination upon loss of power from a primary electrical power source, e.g., upon loss of AC power from a municipal electrical power supply grid. Elevator code requirements currently specify that at least two lamps must run continuously for a minimum of 4 hours in an emergency backup lighting mode, and longer run times are obviously preferable. Some elevator codes may also require that two independent “strings” of lamps operate during an emergency. It can be a challenge to design an elevator interior illumination assembly to be efficient enough to provide 4 hours of lighting where two LED lamps must be operated on two independent circuits from an onboard battery backup power source—especially where, as is the current practice, the two LED lamp circuits are provided conditioned DC power by an LED driver that receives AC power from an inverter that receives DC power from one or more batteries.